Electronic transaction and information services (hereafter referred to as electronic services) are provided either by giving users shared access through some communication network to a database, or by supplying to each user a copy of a database (on a diskette, CD-ROM etc.) which is then accessed locally. User interactions and information display are realized through a computing device with appropriate display capabilities. Shared databases can change dynamically and these changes are then made rapidly available to the users. Published databases do not change between publications. Changes to the source database(s) are made available to users only upon publication of updates.
A principal advantage of a publication approach to electronic services compared to a shared database is its low-cost, mastering and mailing a CD-ROM or diskette being relatively inexpensive. Furthermore, publication removes the telecommunication network bandwidth constraint for broadband information access, such as multimedia, since no remote access is required.
The shared access approach, on the other hand, enables multiple users to share the same information space and thus interact with each other, together with the opportunity to provide electronic transaction services. Unlike local, static database systems, shared database systems can offer current and up-to-date information. Volatile types of information, such as stock prices or news services, are usually provided through shared access.
With the advent of low-cost computing devices capable of manipulating digitized movies, sounds and images, it has become very desirable to use these capabilities in electronic services implementing multimedia data transmission. Because of the possibly very large size of each chunk of multimedia content, timely transmission requires high bandwidth networks. Electronics services using multimedia content are currently provided through the publication of CD-ROMs.
Timeliness of transmission depends on the intended usage of the data. For example, digital teleconferencing requires the transmission and reception of more than 10 video frames per second in addition to the synchronous transmission of digitized sound. Transmission of still picture requested by an on line user, on the other hand, should be delivered within a few seconds.
POTS service has a maximum bandwidth of 64 Kbaud. This low bandwidth currently prohibits electronic service providers from providing multimedia content. The POTS is and for the next few years will be the only ubiquitous, low-cost, point-to-point telecommunication network. Providers of electronic services accessed through POTS must currently restrict themselves to the delivery of data with low bandwidth requirements, such as plain text or low resolution vector-encoded graphics.
Low-cost, high-capacity secondary storage technologies are evolving rapidly, spurring the growth of the multimedia computing market. CD-ROM technologies currently provide the cheapest medium on which to store large quantities of data. Large capacity storage devices (&gt;100 megabytes per device) are necessary to accommodate the space requirements of digitized video, sound and images. A number of standards for CD-ROM formats exist such as Phillips' CD-I.
Recently, attention has moved to the compression, transmission and decompression of multimedia content (digitized video, pictures and sounds). Specialized algorithms (JPEG, streaming-JPEG, MPEG etc.) have been devised to reduce size prior to transmission and to recreate multimedia content on the delivery site with more or less information loss incurred in the process. These algorithms are realized both in software and hardware. Network technology is rapidly evolving to address the high-bandwidth requirement of interactive multimedia. Network bandwidth is expanded by a combination of improved transport capabilities (fiber optics, ISDN, etc.) and more efficient information routing protocols (ATM, FDDI etc.).
Whereas data compression and real-time data decompression can reduce bandwidth requirements on a network by a factor up to 50, this may not be enough to sustain interactivity with multimedia content transmitted over low bandwidth networks.
An economical solution allowing interactive access over the existing POTS to electronic services rich in multimedia content would help expand the mass appeal of these services. The current solution is for electronic service providers to wait for ISDN or other high-bandwidth communication network to reach a sufficiently large portion of the population before adding multimedia content and capabilities to their services.
Videotext services have, for many years, used the POTS to transmit text and vector-encoded graphics to personal computers and public information displays. A considerable amount of work has gone into fully specifying graphic images with a minimal amount of information in order to achieve low-cost transmission and efficient decoding and reconstruction at the site of delivery. The NAPLPS (the North American Presentation Level Protocol Standard) videotext format is a widely used example. The Prodigy.TM. service uses NAPLPS. Videotext technology does not address multimedia content.
In view of the above, it would be desirable to reduce the bandwidth requirements to a telecommunication network for providing interactive electronic services with multimedia content.
Also, it would be desirable to provide a low-cost multimedia system for electronic services through a low-bandwidth network.